David Lindenmayer

Fenner School of Environment and Society

Population, the environment (and biodiversity loss as an indicator)

Impact of the human population (Ehrlich & Holdren)

I = P x A x T

where: I = Impact

P = absolute size of population

A = per capita consumption (affluence)

T = environmental damage in supplying each unit of

consumption

2

IPAT revisited

• We lack a variable that captures ecosystem condition (e.g. biodiversity loss)

• Escalating impacts of resource extraction and consumption – on ecosystems & biodiversity (“T” is increasing)

4

Supercharged IPAT (Davidson & Andrews, 2013)

• Much harder to extract resources than before

• Concentration of ore bodies and other resources declining dramatically (G. Mudd 2013)

• Barrel of oil extracted now >> impact cf 1950s

• Even if popn or consumption constant, ecological impact of resource extraction can increase

More than IPAT now

• Water and GHG costs of extraction and treatment/processing is large and increasing (e.g. 13 900 tonnes of Co2 for each tonne of gold) (25kg of Co2 for each tonne of bauxite) (G. Mudd, 2013)

• Several BILLION tonnes of waste rock and tailings every year (G. Mudd, 2013)

Super Pit open cut gold mine on the outskirts of Kalgoorlie

Great Australian Bight

Gulf of Mexico oil spill

Pillaga CSG

• >22 million people – > 93% urbanised>22 million people – > 93% urbanised

• High population growth rateHigh population growth rate

• Massive resource use (to support SOL)Massive resource use (to support SOL)

• High per capita energy consumptionHigh per capita energy consumption

• High environmental impact (biodiversity High environmental impact (biodiversity

loss)loss)

The human dimensionThe human dimension

The human dimensionThe human dimension

Australia’s population by 2050 = 30-40+ Australia’s population by 2050 = 30-40+ million??million??

Another 90 cities the size of Canberra or Another 90 cities the size of Canberra or Sydney and Melbourne as mega-cities of 8-Sydney and Melbourne as mega-cities of 8-10 million 10 million

(Foran & Poldy 2002)(Foran & Poldy 2002)

New suburbs in ACT

Much urban expansion is into woodlands and grasslands that are nationally endangered ecosystems

Correlation between human population density and species richness (Luck et al. 2004)

Percentage of range-restricted species in each group

Percentage of threatened species in each group

Data for all species in Australia

But (perhaps) ironically…….

• Northern Australia is likely to be where we can make the most cost-effective environmental and conservation gains

The “cost of each person” in Australia

• 200 tonnes of natural resources per year (cf 60 in USA cf 30 in Japan (Foran et al. 2002)

• 24 tonnes of Co2 per capita per year (twice OECD average, 4X world average)

The “cost of each person” in Australia

• Each additional resident costs $340K wrt extra built assets required

• $220 billion for extra 600 000 people in western Sydney alone in next 20 years

• Other costs = impacts on environment & diverted resources from addressing environmental problems

Other “costs” of Australian population

• ??Feeding the rest of the world

• BUT depleting the nation’s environmental infrastructure (i.e. the ecosystems that provide food and fiber)

How will we feed the extra people?

(Australia to feed the world?)

Agricultural intensification is NOT Agricultural intensification is NOT possible in some Australian possible in some Australian

ecosystemsecosystems

But there are significant issues with over-clearing – especially wrt biodiversity loss

Southern Australia – “partial food bowl”

New Zealand dairy industry

Oil palm in SE Asia = feedstock for NZ Dairy Industry

• Land capability mapping and Land capability mapping and

assessment dating back to the 1960s assessment dating back to the 1960s

from CSIRO (LUR)from CSIRO (LUR)

• Limited capability for agriculture Limited capability for agriculture

over vast parts of Northern Australiaover vast parts of Northern Australia

• Large parts of the continent will Large parts of the continent will

become degraded with intensification become degraded with intensification

= “Morocco” potential= “Morocco” potential

Northern Australia – not the food bowl of Asia

• The human population HAS large impacts on the environment – with the status of biodiversity a crude indicator of impact – even if its impact is offset (and is somewhere else = e.g. NZ)

The human dimensionThe human dimension

20 April 2023

AUSTRALIA AUSTRALIA the population, the population,

environmental, and environmental, and education paradox?education paradox?

20 April 2023

One of the richest nations biologically One of the richest nations biologically in the worldin the world

One of the most environmentally One of the most environmentally degraded nations in the worlddegraded nations in the world

A well educated population – but not A well educated population – but not well educated in population issues, well educated in population issues, long-term long-term ECOLOGICALECOLOGICAL sustainability sustainability and biodiversity conservation (as an and biodiversity conservation (as an indicator of sustainability)indicator of sustainability)

The need for “real” debate

Population growth ≠ economic wealth

Population growth needs to be discussed as a major issue – separated from racist and religious debates (SEWPAC)

Relationship between population size, levels of consumption, land degradation and biodiversity loss MUST be discussed